August 17, 2004
Glass Coating Reflects More Heat At Higher Temperatures
A vanadium dioxide derivative with a precise amount of added tungsten automatically lets in more infrared light when the temperature is cold than it does when the temperature is warmer.
Soaring air conditioning bills or suffering in the sweltering heat could soon be a thing of the past, thanks to University College London chemists.
Reporting in the Journal of Materials Chemistry, researchers reveal they have developed an intelligent window coating that, when applied to the glass of buildings or cars, reflects the sunís heat so you donít get too hot under the collar.
While conventional tints block both heat and light the coating, which is made from a derivative of vanadium dioxide, allows visible wavelengths of light through at all times but reflects infrared light when temperature rise over 29 degrees Celsius. Wavelengths of light in this region of the spectrum cause heating so blocking infrared reduces unwanted rays from the sun.
The coatingís ability to switch between absorbing and reflecting light means occupants benefit from the sunís heat in cooler conditions but when temperatures soar room heating is reduced by up to 50 per cent.
Professor Ivan Parkin, of UCLís Department of Chemistry and senior author of the paper, says:
ďTechnological innovations such as intelligent window coating really open the door to more creative design. The current trend towards using glass extensively in building poses a dilemma for architects. Do they tint the glass, which reduces the benefit of natural light or face hefty air conditioning bills?
Professor Parkin says the next item on their research agenda is to investigate the durability of the coating and also to change its color.
Better materials for windows, walls, ceilings, and doors could greatly reduce the amount of energy used for heating and cooling.
This is thoroughly good news, and I hope that it will go into car windows first, then into home and commercial building windows next. If this new coating is used extensively enough, it should save a few critical percent of heating and air conditioning energy bills, as well as making us a little more comfortable.
Now, can this functional coating be combined with one that turns black clear across the UV--visible--IR spectrum, in a matter of microseconds in the face of a very intense flash, to protect against the light and heat flash from an atomic fireball? And, ahem, how much is all this going to cost?
That's awesome. So many exciting new materials coming out. I am concerned about cost though, to be useful to homes it has to be cheaper than running an air conditioner to remove the same amount of heat it deflects.
Maybe not, Patri. There's also the cost of blinds or draperies. Plus, once the mortgage is paid off, many of us might just like the aesthetics of the new glass. If the energy savings is close to cost-effective, electric companies might even subsidize residential installations, since it would be a small recurring cost, much easier to budget for than building additional generators. Let's hope this stuff is affordable!
Where I live in Los Angeles County this glass would have to be quite expensive not to compare favorably to a single summer's air conditioning cost. As it is right now we just drip sweat during the day until the evening brings relief. When I get called out for an onsite job I look forward to the AC as much as the money. A one-time investment of up to $1500 (assuming these things have a lifetime measured in a at least a decade)for the major glass surfaces of this house would be well within reason.
Automatic switching based on temperature isn't bad, but if you can make a pane of glass which can be a window or a mirror at will you've got a far more powerful mechanism for both thermal and light control.
All of you forget that ALL of our 'air conditioning' bills are going up.
And up. Among other things..
For example, deaths from heat waves are projected to *triple* in LA by 2030
The sea level could go up too.
And what about the Santa Monica/Orange County 'Tornado Alley'?